/*
 * Copyright 2006 Jeremias Maerki in part, and ZXing Authors in part
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * This file has been modified from its original form in Barcode4J.
 */

package com.google.zxing.pdf417.encoder;

import com.google.zxing.WriterException;

/**
 * PDF417 error correction code following the algorithm described in ISO/IEC 15438:2001(E) in
 * chapter 4.10.
 */
final class PDF417ErrorCorrection {

    /**
     * Tables of coefficients for calculating error correction words
     * (see annex F, ISO/IEC 15438:2001(E))
     */
    private static final int[][] EC_COEFFICIENTS = {
            {27, 917},
            {522, 568, 723, 809},
            {237, 308, 436, 284, 646, 653, 428, 379},
            {274, 562, 232, 755, 599, 524, 801, 132, 295, 116, 442, 428, 295,
                    42, 176, 65},
            {361, 575, 922, 525, 176, 586, 640, 321, 536, 742, 677, 742, 687,
                    284, 193, 517, 273, 494, 263, 147, 593, 800, 571, 320, 803,
                    133, 231, 390, 685, 330, 63, 410},
            {539, 422, 6, 93, 862, 771, 453, 106, 610, 287, 107, 505, 733,
                    877, 381, 612, 723, 476, 462, 172, 430, 609, 858, 822, 543,
                    376, 511, 400, 672, 762, 283, 184, 440, 35, 519, 31, 460,
                    594, 225, 535, 517, 352, 605, 158, 651, 201, 488, 502, 648,
                    733, 717, 83, 404, 97, 280, 771, 840, 629, 4, 381, 843,
                    623, 264, 543},
            {521, 310, 864, 547, 858, 580, 296, 379, 53, 779, 897, 444, 400,
                    925, 749, 415, 822, 93, 217, 208, 928, 244, 583, 620, 246,
                    148, 447, 631, 292, 908, 490, 704, 516, 258, 457, 907, 594,
                    723, 674, 292, 272, 96, 684, 432, 686, 606, 860, 569, 193,
                    219, 129, 186, 236, 287, 192, 775, 278, 173, 40, 379, 712,
                    463, 646, 776, 171, 491, 297, 763, 156, 732, 95, 270, 447,
                    90, 507, 48, 228, 821, 808, 898, 784, 663, 627, 378, 382,
                    262, 380, 602, 754, 336, 89, 614, 87, 432, 670, 616, 157,
                    374, 242, 726, 600, 269, 375, 898, 845, 454, 354, 130, 814,
                    587, 804, 34, 211, 330, 539, 297, 827, 865, 37, 517, 834,
                    315, 550, 86, 801, 4, 108, 539},
            {524, 894, 75, 766, 882, 857, 74, 204, 82, 586, 708, 250, 905,
                    786, 138, 720, 858, 194, 311, 913, 275, 190, 375, 850, 438,
                    733, 194, 280, 201, 280, 828, 757, 710, 814, 919, 89, 68,
                    569, 11, 204, 796, 605, 540, 913, 801, 700, 799, 137, 439,
                    418, 592, 668, 353, 859, 370, 694, 325, 240, 216, 257, 284,
                    549, 209, 884, 315, 70, 329, 793, 490, 274, 877, 162, 749,
                    812, 684, 461, 334, 376, 849, 521, 307, 291, 803, 712, 19,
                    358, 399, 908, 103, 511, 51, 8, 517, 225, 289, 470, 637,
                    731, 66, 255, 917, 269, 463, 830, 730, 433, 848, 585, 136,
                    538, 906, 90, 2, 290, 743, 199, 655, 903, 329, 49, 802,
                    580, 355, 588, 188, 462, 10, 134, 628, 320, 479, 130, 739,
                    71, 263, 318, 374, 601, 192, 605, 142, 673, 687, 234, 722,
                    384, 177, 752, 607, 640, 455, 193, 689, 707, 805, 641, 48,
                    60, 732, 621, 895, 544, 261, 852, 655, 309, 697, 755, 756,
                    60, 231, 773, 434, 421, 726, 528, 503, 118, 49, 795, 32,
                    144, 500, 238, 836, 394, 280, 566, 319, 9, 647, 550, 73,
                    914, 342, 126, 32, 681, 331, 792, 620, 60, 609, 441, 180,
                    791, 893, 754, 605, 383, 228, 749, 760, 213, 54, 297, 134,
                    54, 834, 299, 922, 191, 910, 532, 609, 829, 189, 20, 167,
                    29, 872, 449, 83, 402, 41, 656, 505, 579, 481, 173, 404,
                    251, 688, 95, 497, 555, 642, 543, 307, 159, 924, 558, 648,
                    55, 497, 10},
            {352, 77, 373, 504, 35, 599, 428, 207, 409, 574, 118, 498, 285,
                    380, 350, 492, 197, 265, 920, 155, 914, 299, 229, 643, 294,
                    871, 306, 88, 87, 193, 352, 781, 846, 75, 327, 520, 435,
                    543, 203, 666, 249, 346, 781, 621, 640, 268, 794, 534, 539,
                    781, 408, 390, 644, 102, 476, 499, 290, 632, 545, 37, 858,
                    916, 552, 41, 542, 289, 122, 272, 383, 800, 485, 98, 752,
                    472, 761, 107, 784, 860, 658, 741, 290, 204, 681, 407, 855,
                    85, 99, 62, 482, 180, 20, 297, 451, 593, 913, 142, 808,
                    684, 287, 536, 561, 76, 653, 899, 729, 567, 744, 390, 513,
                    192, 516, 258, 240, 518, 794, 395, 768, 848, 51, 610, 384,
                    168, 190, 826, 328, 596, 786, 303, 570, 381, 415, 641, 156,
                    237, 151, 429, 531, 207, 676, 710, 89, 168, 304, 402, 40,
                    708, 575, 162, 864, 229, 65, 861, 841, 512, 164, 477, 221,
                    92, 358, 785, 288, 357, 850, 836, 827, 736, 707, 94, 8,
                    494, 114, 521, 2, 499, 851, 543, 152, 729, 771, 95, 248,
                    361, 578, 323, 856, 797, 289, 51, 684, 466, 533, 820, 669,
                    45, 902, 452, 167, 342, 244, 173, 35, 463, 651, 51, 699,
                    591, 452, 578, 37, 124, 298, 332, 552, 43, 427, 119, 662,
                    777, 475, 850, 764, 364, 578, 911, 283, 711, 472, 420, 245,
                    288, 594, 394, 511, 327, 589, 777, 699, 688, 43, 408, 842,
                    383, 721, 521, 560, 644, 714, 559, 62, 145, 873, 663, 713,
                    159, 672, 729, 624, 59, 193, 417, 158, 209, 563, 564, 343,
                    693, 109, 608, 563, 365, 181, 772, 677, 310, 248, 353, 708,
                    410, 579, 870, 617, 841, 632, 860, 289, 536, 35, 777, 618,
                    586, 424, 833, 77, 597, 346, 269, 757, 632, 695, 751, 331,
                    247, 184, 45, 787, 680, 18, 66, 407, 369, 54, 492, 228,
                    613, 830, 922, 437, 519, 644, 905, 789, 420, 305, 441, 207,
                    300, 892, 827, 141, 537, 381, 662, 513, 56, 252, 341, 242,
                    797, 838, 837, 720, 224, 307, 631, 61, 87, 560, 310, 756,
                    665, 397, 808, 851, 309, 473, 795, 378, 31, 647, 915, 459,
                    806, 590, 731, 425, 216, 548, 249, 321, 881, 699, 535, 673,
                    782, 210, 815, 905, 303, 843, 922, 281, 73, 469, 791, 660,
                    162, 498, 308, 155, 422, 907, 817, 187, 62, 16, 425, 535,
                    336, 286, 437, 375, 273, 610, 296, 183, 923, 116, 667, 751,
                    353, 62, 366, 691, 379, 687, 842, 37, 357, 720, 742, 330,
                    5, 39, 923, 311, 424, 242, 749, 321, 54, 669, 316, 342,
                    299, 534, 105, 667, 488, 640, 672, 576, 540, 316, 486, 721,
                    610, 46, 656, 447, 171, 616, 464, 190, 531, 297, 321, 762,
                    752, 533, 175, 134, 14, 381, 433, 717, 45, 111, 20, 596,
                    284, 736, 138, 646, 411, 877, 669, 141, 919, 45, 780, 407,
                    164, 332, 899, 165, 726, 600, 325, 498, 655, 357, 752, 768,
                    223, 849, 647, 63, 310, 863, 251, 366, 304, 282, 738, 675,
                    410, 389, 244, 31, 121, 303, 263}};

    private PDF417ErrorCorrection() {
    }

    /**
     * Determines the number of error correction codewords for a specified error correction
     * level.
     *
     * @param errorCorrectionLevel the error correction level (0-8)
     * @return the number of codewords generated for error correction
     */
    static int getErrorCorrectionCodewordCount(int errorCorrectionLevel) {
        if (errorCorrectionLevel < 0 || errorCorrectionLevel > 8) {
            throw new IllegalArgumentException("Error correction level must be between 0 and 8!");
        }
        return 1 << (errorCorrectionLevel + 1);
    }

    /**
     * Returns the recommended minimum error correction level as described in annex E of
     * ISO/IEC 15438:2001(E).
     *
     * @param n the number of data codewords
     * @return the recommended minimum error correction level
     */
    static int getRecommendedMinimumErrorCorrectionLevel(int n) throws WriterException {
        if (n <= 0) {
            throw new IllegalArgumentException("n must be > 0");
        }
        if (n <= 40) {
            return 2;
        }
        if (n <= 160) {
            return 3;
        }
        if (n <= 320) {
            return 4;
        }
        if (n <= 863) {
            return 5;
        }
        throw new WriterException("No recommendation possible");
    }

    /**
     * Generates the error correction codewords according to 4.10 in ISO/IEC 15438:2001(E).
     *
     * @param dataCodewords        the data codewords
     * @param errorCorrectionLevel the error correction level (0-8)
     * @return the String representing the error correction codewords
     */
    static String generateErrorCorrection(CharSequence dataCodewords, int errorCorrectionLevel) {
        int k = getErrorCorrectionCodewordCount(errorCorrectionLevel);
        char[] e = new char[k];
        int sld = dataCodewords.length();
        for (int i = 0; i < sld; i++) {
            int t1 = (dataCodewords.charAt(i) + e[e.length - 1]) % 929;
            int t2;
            int t3;
            for (int j = k - 1; j >= 1; j--) {
                t2 = (t1 * EC_COEFFICIENTS[errorCorrectionLevel][j]) % 929;
                t3 = 929 - t2;
                e[j] = (char) ((e[j - 1] + t3) % 929);
            }
            t2 = (t1 * EC_COEFFICIENTS[errorCorrectionLevel][0]) % 929;
            t3 = 929 - t2;
            e[0] = (char) (t3 % 929);
        }
        StringBuilder sb = new StringBuilder(k);
        for (int j = k - 1; j >= 0; j--) {
            if (e[j] != 0) {
                e[j] = (char) (929 - e[j]);
            }
            sb.append(e[j]);
        }
        return sb.toString();
    }

}
